The present invention generally relates to musical instruments, and more specifically to a device primarily for stringed musical instruments which can sustain the sounds originally produced on the instrument.
While the basic principle of the present invention can be applied to most musical instruments, as will become evident hereafter, the description that follows is directed primarily at stringed musical instruments. As is well known, playing a stringed instrument involves plucking the strings and setting them into vibratory motion. The vibrations of the strings disturb the surrounding air and these air disturbances are perceived by a human ear as the musical sounds which are played. Under normal circumstances, once a string has been plucked and set into motion, the amplitude of the vibrations have an initial predetermined value and thereafter the amplitude or magnitude of the vibrations continuously decrease or decay until vibrations cease totally and the string reverts to its initial stationary state. The rate of decay or the time constant involved with each of the strings is a function of numerous factors including, but not limited to, the density of the material from which the string is made, its physical dimensions, the tension of the string and the like.
Frequently, in order to produce special sound, sound effects or moods, musicians find it necessary or desirable to sustain a musical sound produced by, for example, a string of a musical instrument for a period of time which is greater than that normally associated with the time constants of the string.
With the development of electronic equipment in the mid-1930's, it was learned that by placing an electromagnetic pick-up (microphone or transducer) on a steel string guitar, the sound of that instrument could be amplified. With further development of amplification equipment in the 1940's came the emergence of a new type of guitar commonly called the "Electric" or "Solid Body" guitar. In this type of guitar the neck and body of the instrument serve only as a means of generating the original notes. The instrument basically has no acoustical qualities. The vibrating strings are sensed by the magnetic pick-ups and a musician adjusts his amplifier for volume and tonal qualities.
In about 1953, a new type of music evolved, and with it a new method of playing the electric guitar. It was in and around that time that the concept of sustaining the musical sounds of an electric guitar first developed and became widely used. The music was almost of necessity loud. By using large amplifiers and speakers, the musicians could send the notes from their speakers back to the strings of the guitar, causing a sympathetic vibration to occur which would reinforce the vibratory movements of the strings and thereby sustain the sound produced by the instrument. In effect, acoustic feedback was utilized to complete a regenerative acoustic loop. It was the exploitation of this regenerative effect that created what we recognize today as the electric guitar sound.
There has been, however, little progress since the above-described early developments. The previous or older methods, as well as those used today, which use regenerative feedback, depend on room accoustics, the type of amplifiers and speakers used and the volume of the amplified sound. In the prior art arrangements, then, the same external speakers that are used to generate the sound to the listening audience are also used in the regenerative feed-back arrangement to drive the strings. The external speakers used, which are normally spaced a considerable distance from the musicians and, therefore, from the strings of the musical instrument, are of necessity played at a very high volume or loudness. The prior art approach has not worked satisfactorily where the external speakers are driven at a moderate or low volume since the accoustic feedback is not sufficient in that instance to drive the strings and to sustain the sound. Under certain conditions, and with certain room accoustics, the loudness of the sound necessary to produce sustain on a musical instrument such as a guitar is such as to be uncomfortable to a listener.
Since "solid body" guitars basically lack acoustic qualities, the guitar could only be played and heard when connected to external speakers which are normally large and bulky. The external speakers and the amplifiers associated with most electric guitars make it difficult or at best inconvenient to easily transport the electric guitar system.